Impregnation of fibrous materials



Patented Apr. 27, 1943 MPREGNATION OF FIBROUS MATERIALS Erich, Schuelke,deceased, late 01' Saddle River, N. J., by Amielotte Schuelke,'administratrix,

Saddle River, vN. J.

No Drawing. Application February 24, 1941, Serial No. 380,314

7 Claims.

This invention relates to improvements in the art of impregnatingfibrous materials. The invention is especially applicable forimpregnating and hardening of sheets, plates, blocks, etc., such as usedin clutches, brakes, etc., when thorough oxydation by air is notpossible. I

It has always been a problem to impregnate fibrous materials, such asasbestos, with a binder which will withstand exposure to hightemperatures, particularly when the fibrous material consists of thicksheets or plates. Impregnation by drying oils, unless especiallyprepared, does not give satisfactory results under such conditions, asin the case of thick plates the oxygen of the air cannot penetrate intothe center of such plates, in order to effect drying by oxydation.Therefore, the center will remain softer than the outside.

. A typical example for such conditions is a molded brake blockcompounded from asbestos fiber and other solids with an oil as binder.These brake blocks are cured by exposure to a temperature of 350 to 450degrees Fahrenheit for many hours. Linseed oil, bodied under vacuum to ahigh viscosity with very low acidity has been found to be the mostsuitable material for the purpose, also in combination with phenolicr'esins. I

The present invention utilizes principally cheap raw materials having ahigh degree of polymerization and a high acidity, such as still bottomsfrom the distillation of fatty acids.

Such materials consist principally of poly merized triglycerides andfatty acids, the latter also mostly polymerized. The presence of thesefree acids prevents the coagulation of the still bottoms at the hightemperatures prevailing in the fatty acid stills. The fact that the freefatty acids are present in the form of dimers or higher polymersexplains the impossibility to distill them off under the vacuum andtemperature under which the corresponding monomeric acids distill over.

He discovered that such still bottoms, when heated with polyhydricalcohols, e. g. glycerin, in a quantity suificient to esterify the freefatty acids in the still bottoms to a point, where all the alcohol iscombined to' form mono or diesters, the resulting material forms anexcellent impregnating and. coating base, which upon baking at the usualtemperatures of 350 to 450 degrees Fahrenheit solidifies completely dueto the completion of esteriflcation, and becomes insoluble and infusibleby heat.

He also discovered that such partially esterified still bottoms areexcellent solvents for phenolic resins, probably due to the freehydroxyl groups. In cases where greater hardness of the polymerizedbinder is required, a solution of such resins in the partiallyesterified compound was found to be very suitable.

Not only still bottoms, but drying and semidrying oils can be utilizedaccording to the present invention. As such oils he mentioned linseedoil, perilla oil, China-wood oil, oiticia oil, raw or dehydrated castoroil, walnut oil, poppy seed oil, rapeseed oil, soya bean oil, sunfloweroil, fish oils, tall oil, and oils of similar chemical composition.

In utilizing these oils, they are first bodied under heat with orwithout the addition of fatty acids to a high degree of polymerizationand high viscosity. Then a polyhydric alcohol, such as glycerin,sorbitol, pentaerithritol, is added in pressure, without, or preferablywith mechanical agitation, under cover of inert gases, such as carbondioxide or nitrogen, in vessels heated by direct fire, electrically orthrough a jacket, or in any other manner known to the industry ofvarnish manufacture, oil bodying or resin manufacture.

While a temperature of 400 degrees F. is generally used in the examplescited, a lower temperature is usable particularly when vacuum is appliedand. low viscosities are desired. Higher temperatures may be appliedespecially when less polymerized raw materials are used and when higherviscosities are desired in the finished product.

Compounds made according to this invention are suitable for manypurposes, e. g. impregnation of gaskets, brake lining and clutch facing,asbestos shingles and tile, etc., also as coating material, priming andfinishing coat "on asbestos materials, on steel, cast iron and othermetals, in the form of sheets, wire, cast or machined parts.Particularly waterproof finishes are obtained by incorporation ofsuitable phenolic resins or com- Example 1 100 parts of still bottomsfrom the distillation of linseed-oil fatty acids with an acid value of90 are heated with v parts of glycerin to a temperature of 400 degreesF. under carbon dioxide until the acid value is below 20. Then theproduct is cooled rapidly. The oil thus obtained has a viscosity of 500poises or more (depending on the degree of polymerization of the rawmaterial), is soluble in hydrocarbon solvents, and when coated on ametal sheet and baked at 350 degrees F. for 2 hours forms a hard, toughfilm of good elasticity, infusible by heat and sparingly soluble in allorganic solvents.

Example 2 100 parts of soya beanioil pitch (still bottoms from thedistillation of soya bean fatty acids) with an acid value of 100 areheated with parts of castor oil to a temperature of 450 degrees F. for 1hour, then for one half hour at 550 degrees F'., then cooled to 400 F.,and 5% parts of glycerin are=added and heating at 400 degrees F.continued, until the acid value of the product is below 25.

The product thus obtained is a viscous, brown oil suitable as binder for,asbestos fibers in the manufacture of brake linings and clutch facingin place of vacuum bodied linseed oil. The drying-of the impregnatedlining is effected by bakingiat 300 degrees F. or more. Lining of oneinch or more thickness is thoroughly cured in the center.

Example 3 parts of ,p-tertiary-butyl-phenol formaldehyde resin aredissolved by heating to 300 degrees F. in 80 parts of cotton seed pitch.Then 4 parts of glycerin are added and the mass poises at 70 degrees I".Then the acid value is obtained by titration of a sample and after themass is allowed to cool to 400 degrees F., glycerin is slowly added inan amount of 1.2 times the theoretical amount calculated from the acidvalue. Heating is continued without reflux until the acid value is below25.

A medium light colored oil is obtained of high viscosity, which dries toa very durable film when baked at temperatures above 250 degrees I". andis suitable as coating and impregnating material.

What is claimed is:

1. In the art of impregnating of fibrous materials those steps whichconsist in adding to a mixture of polymerized fatty acids andpolymerized fatty acid esters an amount of polyhydric alcoholssubstantially sufficient to esterify all the free fatty acids containedin said mixture; in esterifying at first only a part of said free fattyacids with said polyhydric alcohols to obtain a viscousoil; inimpregnating the fibrous materials to be treated with said viscous oil;in solidifying said oil by subjecting the impregnated materials to abaking process to substantially finish the esterification of the freeacids contained in said mixture.

2. In the art of impregnating of fibrous materials those steps whichconsist 'in adding to a mixture of polymerized fatty acids andpolymerized fatty acid esters an amount of polyhydric alcoholssubstantially sufficient to esterify all the free fatty acidscontainedin said mixture; in esterifying at first only a part of said free fattyacids with said polyhydric alcohols to obtain a viscous oil; indissolving an oil-soluble resin in the raw mixture or in the productresulting from the partial esterification of said mixture; inimpregnating the fibrous materials to be treated with said viscous oil;in solidifying said oil by subjecting the impregnated material to abaking process to substantially finish v the esterification of the freeacids contained in heated at 400 degrees F. until a sample upon 7cooling has a viscosity of 500 poises. Then the mass is cooled rapidlyto avoid coagulation.

The resulting product gives a harder drying coating or impregnation ofeven better water resistance than the products from Examples 1 and 2,and is completely infusible and almost insoluble in any solvent.

Example 4 20 parts of oiticia oil. parts of linseed pitch, 20 parts oftall oil and 10 parts of phthalic anhydride are heated with 16 parts ofsorbitol (85%) to 410 degrees F. with good agitation and after one halfhour also under vacuum, until the acid value of the mixture is below 30,then the mass is cooled to 250 degrees F. and 50 parts of toluol areadded.

The resulting varnish is suitable as insulating varnish for wire coatingof excellent hardness and flexibility.

Example 5 80 parts of raw linseed oil are heated while carbon dioxide ispassed through the oil with 20 parts of fatty acids. obtained bysaponification of dehydrated castor oil to a temperature of 580 degreesF. until the viscosity of a sample is 35 said mixture.

3. In the art of impregnating of fibrous ma-' terials, the processconsisting in esterifying a part of the free acids contained in stillbottoms from the distillation of fatty acids with polyhydric alcohols;in applying the liquid product resulting from the partial esterificationto the material to be impregnated and in substantially finishing theesterification of the free acids contained in said still bottoms, bysubjecting said material to a baking process.

4. In the manufacture of brake linings and clutch facings the process ofthoroughly impregnating and binding together the asbestos fibers of thelinings, comprising the heating of still bottoms from the distillationof fatty acids with polyhydric alcohols to partially esterify said stillbottoms; impregnating the asbestos fibers of said linings with theviscous oil resulting from said partial esterification of said stillbottoms and subjecting the linings, to a baking process.

5. In the manufacture of brake linings and clutch facings the process ofthoroughly impregnating and binding together the asbestos fibers of thelinings, comprising the heating of still bottoms frorn the distillationof soya bean fatty acids with castor oil and glycerin to partiallyesterify said soya bean oil pitch; impregnating the asbestos fibers ofsaid linings with the viscous oil. resulting from said partialesterification of the soya bean oil pitch and subjecting the linings, toa baking process.

in the presence of fatty acids obtained by the 6. In the art ofimpregnating offibrous materials, the process consisting in'polymerizing drying oils in the presence of fatty acids to highviscosity; in partially esterifying the free acids contained in saidpolymerized drying oils with polyhydric alcohols; .in applying theproduct resulting from the partial esterification to Y the material tobe impregnated and in substantially finishing the esteriflcation of thefree acids contained in said polymerized drying oils by subjecting saidmaterial to a baking process.

7. The process of impregnating of fibrous materials, consisting inpolymerizing raw linseed oil saponiflcation of dehydrated castor oil, inadding an amount 01 glycerine substantially suflicient to esterify allthe free fatty acids contained in said polymerized products; inpartially esterifying the free acids contained in said polymerizedproducts; in applying the resulting oil to the material to beimpregnated and in substantially finishing the esterification bysubjecting said ma-- terial to a baking process.

ANNELO'I'I'E SCHUELKE, Administmtria: of the Estate of Erich Schuelke,

deceased.

